This invention relates generally to dental prostheses and more particularly relates to the replacement of teeth using a biologically compatible, non-resorbable, endostial implant.
The loss of one or more teeth by disease or trauma results in many undesirable consequences. Mastication becomes more difficult and less efficient. Susceptibility to other disease may be increased and, with the passage of time, migration of the teeth may cause complications including malocclusion.
One of the most common techniques for prosthetic restoration involves the use of a partial denture which may be a tooth-borne, tooth and mucosal-borne, or mucosal-borne prosthesis.
Such prostheses however, have several disadvantages. Because relatively high loads are exerted upon these devices, they tend to move or flex, expecially when dependent upon the soft mucosal tissue for support. They may in fact cause a change in contour with substantial loss of the underlying supporting tissue. Furthermore, reshaping of healthy teeth to permit the attachment of the partial denture by means of a clasp, or any of a number of other intracoronal or extracoronal attachments, is often required.
One of the primary disadvantages of partial dentures is the fact that the partial denture receives marginal load support from the underlying alveolar bone at the vacant tooth site or sites, thus forcing the transfer of abnormal lateral stresses to abutting teeth with destruction of peridontal tissues.
Attempts have been made to implant relatively rigid structures within or upon the alveolar bone in a region of one or several contiguous vacant tooth sites. For example, others have implanted a relatively flat, metallic, endosseous blade formed with a plurality of holes or vents. The vents are intended to permit bone to grow through the lock and implant in place. Such metallic blades, known as Linkow vent blade implants, are formed with a truncated, pyramidal or conically shaped flat mounting post which is undercut, where it is attached to the blade portion of the implant. The metallic blades, however, have met with very limited success as a high rate of failure has been experienced.
Implants of carbon have also been attempted, but it has been found that with metallic, and to a lesser extent with carbon, implants the body typically tends to wall off the implant by soft tissue encapsulation which grows as a protective interface between the alveolar bone and the implant. This is a typical host rejection phenomenon. The implant becomes liable to movement, eventually loosens and is lost.
Still others have searched for porous materials believing porosity to be important. The supposition is that the bone tissue or other tissue will grow firmly into the pores of the implant to provide rigid support. Although this has been a very popular approach, to date the efficacy of this concept in practice is relatively poor.
According to the discovery of the present invention a prosthetic implant is disclosed which rigidly and durably supports one or more prosthetic crowns, or other prosthesis amenable to construction upon the implant or implants placed within the alveolar bone.